～ている所(ところ)だIn the process of doing ~ right now/at this moment

The grammar point "ている" (te-iru) is used to describe an ongoing action or a state of being. On the other hand, "ているところだ" (te iru tokoro da) is used to express an action that is happening right at the moment, giving a sense of immediacy or urgency to the sentence. While both indicate continuation, "ているところだ" creates a more vivid scene of the action in process.

The Japanese grammar point とき is used to indicate the time when a specific action or event occurs, similar to English's 'when' or 'at the time of'. In contrast, ているところだ is used to express that the speaker or someone else is currently in the process or midst of doing something at this present moment. Therefore, while both phrases are related to time, they connote different temporal nuances; とき relates to a broader unspecific time frame, whereas, ているところだ focuses on the immediate present moment.

The phrase ているところだ in Japanese is used to express that someone is currently in the process of doing something, or it's happening right now at this very moment. On the other hand, ているあいだに is used to indicate an action or event happening concurrently or during the time that another action is taking place. It's the equivalent to saying "while" or "during" in English.

The expression ているところだ emphasizes that something is happening right at this moment and emphasizes the ongoing status of that action. On the other hand, 途中に・途中で refers to being in the middle of a process or on the way to somewhere, not necessarily emphasizing the current ongoing condition. While both indicate an ongoing action, ているところだ focuses on the immediate present, while 途中に・途中で focuses on the process as a whole.

Both ているところだ and 中 can indicate ongoing actions, though there is a slight nuance difference. ているところだ is more focused on the action's exact moment, essentially indicating it's happening "right now," and often used with verbs that represent actions for a certain period. On the other hand, 中 places more emphasis on the duration of the action, highlighting the action is occurring "during" or "throughout" a particular period or process, and is likely to be used when the focus is more on the ongoing situation or context than the action itself.

The phrase "ているところだ" is used when the speaker is emphasizing that they are in the process of doing something right now or at this exact moment. On the other hand, "最中に" is used when the speaker is in the middle of doing something, often emphasizing the ongoing nature of the action rather than the exact current moment. So, while both phrases show ongoing actions, the nuance of "ているところだ" leans more towards the current moment, and "最中に" leans more towards the continuity or duration of the action.

Both ているところだ and うちに are used to indicate something happening concurrently or during a period of time. However, ているところだ tends to be used more to emphasize the state or action taking place right now and gives a more immediate and ongoing impression, while うちに suggests that something should be done or happens in the span of when another action or state is still ongoing, often used in situations where the time or opportunity might be lost if the action is not done during that period.

The grammar point ているところだ is used to describe a situation that is happening or someone's specific activity in progress at the exact moment of speaking, giving a sense of immediacy or urgency. Meanwhile, の間に signifies a span of time during which another event or situation happens. It infers that something else occurs simultaneously or within the given timeframe, illustrating a temporal correlation rather than an immediate, ongoing action.

Both "ているところだ" and "ながら" denote ongoing actions or states, but they are used in somewhat different contexts. "ているところだ" emphasizes that something is happening right now, at this very moment, conveying a strong sense of immediacy. On the other hand, "ながら" is used to express two ongoing actions or states that are happening at the same time, with the main action usually being the latter part of the sentence. It's more about multitasking.

The key difference between "ているところだ" and "ついでに" lies in their roles and nuances in a sentence. "ているところだ" stresses that an action is occurring right at this moment or is in progress, adding a sense of immediacy to the action. On the other hand, "ついでに" is used when one action conveniently takes place at the same time or on the occasion of another action, equivalent to English phrases like "while you're at it" or "by the way".

The grammar point ているところだ shows a current ongoing action, emphasizing the speaker is in the process of doing something at this moment, for example, "話しているところだ" can be translated as "I'm in the middle of talking". On the other hand, the grammar point ～ところに・～ところへ refers to the exact timing of something happening - it could be in the past, present, or future - bringing attention to a certain time point rather than an ongoing action, like when something happens while you are doing something else. For example, "食べるところに電話がかかってきた" would mean "Just as I was about to eat, the phone rang".